Two-stage starting system for internal-combustion engines



April 10, 1945. A. MILLER 5 TWO STAGE STARTING SYSTEM FOR INTERNAL-COMBUSTION ENGINES Filed June 3, 1942 1- 3 0Q @lllllmlk f 5 v 7 INVENT OR.

wiin/asa: v v I Patented Apr. 10, 1945 TWO-STAGE STARTING SYSTEM FOR INTERNAL-COMBUSTION ENGINES Anthony Miller: Elmira, N. Y., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application June 3, 1942, Serial No. 445,577

4 Claims.

The present invention relates to a two stage starting system for internal combustion engines and more particularly to such a system incorporating an automatic delayed action switch for.

controlling the application of full battery voltage v to the Starting motor.

Various .forms of two stage starter controls have been heretofore used for delaying the full energization of the starting motor until after the driving connection to the engine has been established. Their use. however, has been limited to some extent by price considerations and by the factor of undesirable complications.

It is an object of the presentinvention to provide a novel two stage engine starting system which is efiicient and reliable in operation while being simple and economical in construction.

It is another object to provide such a device incorporating a novel form of delayed action switch.

It is another object to provide such a device in which the delayed action of the switch is inherent in its construction and is substantially independent of the functional condition of the starting system.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing, in which:

Fig. 1 is a semi-diagrammatical illustration of a preferred embodiment of the inventionshowing the structure of the switch partly in side elevation and partly in vertical section;

Fig. 2 is a similar view showing the parts in the positions assumed immediately after closure of the starting switch; and

Fig. 3 is a similar view showing the parts in the positions assumed when the delayed action switch is closed and the starting motor fully energized.

In Fig. l 01 the drawing there is illustrated a starting system comprising a battery I grounded at 2 and connected by a lead 3 to a starting switch 4. A lead connects the starting switch to one end of a resistor 6, the opposite end of which is connected b a lead I to the starting motor SM which is grounded at 8 to complete the starting circuit. The resistor 6 is of such value as to reduce the voltage of the battery as initially applied to the starting motor to avalue which causes the initial engagement of the starting mechanism to take place without unnecessary shock. I

Means are provided for bridging the resistor B to apply the full battery voltage to the starting motor for cranking purposes. For this purpose fixed contacts 9 and II are connected to the opposite ends of the resistor 6 and a bridging contact I2 is mounted on a magnetic switch plunger 13, in position to cooperate therewith.

According to the present inventionmeans are provided for actuating the switch plunger l3 to close the switch 9. I2, II a predetermined time after closure of the starting switch 4. As here shown. this means comprises a solenoid I4 r-onnected by a lead I5 to the starting motor lead 5, and grounded at l6 so as to be energized from the battery I when the starting switch is closed. Solenoid I4 is provided with a bearing sleeve ll of non-magnetic material extending substantially beyond the ends of the solenoid. The magnetic switch plunger I3 is slidably mounted in one end of the solenoid I4 within the bearing sleeve I'I. Plunger I3 is considerably smaller in diameter than the interior of sleeve I1, and a bushing I 8 of non-magnetic material is mounted on the plunger to slide freely in the sleeve and thus guide the plunger therein. A spring I9 is arranged to yieldingly oppose induction of the plunger into the solenoid.

A second plunger of magnetic material 2| is slidably mounted in the opposite end of the sleeve ll. adjacent the end of the solenoid I4 but not projecting within the solenoid to any substantial degree. This plunger is substantially larger in diameter than the switch plunger I3, so as to fit slidably within the sleeve I1, and aspring 22 is provided for normally maintaining the plunger I in the position shown in Fig. 1 against a stop 20. Separation of the plungers I3 and 2I- is limited by suitable means such as a stem 23 which may be of non-magnetic material sweated or threaded into the switch plunger as shown at M, slidably traversing an axial opening in the plunger 2| and having a stop shoulder 24 at its outer end.

In operation. closure of the starting switch 4 energizes the starting motor with reduced voltage due to the resistor 6, and at the same time energizes solenoid I4 of the bridging swit h. Since the switch plunger I3 extends within the solenoid, energization thereof causes induction of the switch plunger until it s rikes against the end of the plunger 2! as shown in 2, thus moving the bridging contact I2 away from the switch contacts 9 and II. When the switch plunger l3 thus engages the large plunger 2|, the flux of the solenoid It is caused to traverse the large plunger and draw it into the coil, thus projecting the V switch plunger to cause closure of the It? switch as shown in Fig. 3. this stage oi the operation. the two plungers act as a single magnetic plunger of stepped diameter, the poi-=- tion of "large diameter being dominant in its efiort to center itself in the solenoid i l, thereby efiectively holding the bridging switch. closed as long as the starting switch dremains closed.

In order to secure substially uniform conshoull 5%. v I as'raese,

one of the parts oi said plunger being arranged to actuate the contact member; and means whereby initial energization of the switch causes said one part of the plunger to move into engagement with the other said part while moving the contact member away from closed position, after which ,the' two parts of the plunger unite and move together to close the switch.

iii

2. In an engine starting system a starting circult including a starting motor and a resistor for vreducing the initial energization thereof, a mag netic switch for bridging the resistor including normally open contacts, a solenoid, a magnetic '25, provides a delay which is quite uniform and co suficient to ensure engagement of the-starting mech prior to full application of the batt'e'rr voltage to the starting motor. Moreover, this delayed action is secured without the necessity of special design of the solenoid involving extra ounts of conductive materials.

Although but one embodiment of the invention has been shown and described in detail, it will he understood that other embodiments are possible and that various changes may be made in the deso sign and arrangement of the partswithout departing from the spirit of the invention asdei'lned in the claims appended hereto.

What is claimed is:

i. m a two stage starting system for internal cbustion engines a starting circuit including a resistor for reducing the initial flow of current therethrough d an electromagnetic switch for bridging said resistor, said switch including a contact member and a two part movable plunger,

1 a parts.

plunger of small diameter controlling said contacts slidably mounted within one end of the solenoid, a magnetic plunger of larger diameter slidahly mounted adjacent the opposite end of the solenoid, and means for simultaneously energizing the starting motor and said solenoid, said corrtacts being arranged to be closed by the projection of the small plunger from the solenoid by the larger plunger.

3. A delayed action electromagnet including a solenoid and a plunger formed in two coam'al parts, one part of large diameter located normally outside'the eilective zone of influence of the solenoid and the other part of smaller diameter normally spaced therefrom and movable by energiza= tion of the solenoid into engagement therewith whereby the magnetic iiux or the solenoid is con ducted by the part of smaller diameter through said part of large diameter and the solenoid is thereby made efiective to actuate the part of large said.

d. A delayed action electromagnet as set forth in claim 3 including further means attached to one of said parts of the plunger and engageable with the other partthereoi to limit separation of 

